Dentin is the substance between enamel or cementum and the pulp chamber. It is secreted by the odontoblasts of the dental pulp. The formation of dentin is known as dentinogenesis. The porous, yellow-hued material is made up of 70% inorganic materials, 20% organic materials, and 10% water by weight.
Medical Definition of metaplasia. 1  1: transformation of one tissue into another metaplasia of cartilage into bone. 2  2: abnormal replacement of cells of one type by cells of another.
Apocrine metaplasia is sometimes described as a âbenign epithelial alterationâ of breast tissue, which means that epithelial cells are undergoing an unexpected change. The word apocrine means something to do with sweat, but only a resemblance. Itâs not actually sweat gland related.pocrine Metaplasia is a particular kind of cellular change associated with a variety of breast cystic disorders. It is a completely benign condition which in itself does not increase risk for subsequent breast cancer.